ASP.NET Identity的默认密码哈希器-它是如何工作的，它是否安全？
ASP.NET Identity的默认密码哈希器-它是如何工作的，它是否安全？
提问于 2013-12-17 06:08:43
我想知道MVC5和ASP.NET Identity Framework附带的UserManager中默认实现的密码哈希器是否足够安全？如果是这样，你能给我解释一下它是怎么工作的吗？
IPasswordHasher接口如下所示：
public interface IPasswordHasher
{
string HashPassword(string password);
PasswordVerificationResult VerifyHashedPassword(string hashedPassword,
string providedPassword);
}正如你所看到的，它不需要盐，但在这个帖子中提到："Asp.net Identity password hashing“，它实际上在幕后给它加盐。所以我想知道它是如何做到这一点的？这些盐是从哪里来的？
我担心的是盐是静态的，这使得它非常不安全。
回答 3
Stack Overflow用户
回答已采纳
发布于 2013-12-17 06:39:31
下面是默认实现(ASP.NET Framework或ASP.NET Core)的工作方式。它使用带有随机盐的Key Derivation Function来生成散列。盐被包含在KDF的输出中。因此，每次你“散列”相同的密码，你会得到不同的散列。为了验证散列，将输出拆分为salt和其余部分，并使用指定的salt对密码再次运行KDF。如果结果与初始输出的其余部分匹配，则验证散列。
哈希：
public static string HashPassword(string password)
{
byte[] salt;
byte[] buffer2;
if (password == null)
{
throw new ArgumentNullException("password");
}
using (Rfc2898DeriveBytes bytes = new Rfc2898DeriveBytes(password, 0x10, 0x3e8))
{
salt = bytes.Salt;
buffer2 = bytes.GetBytes(0x20);
}
byte[] dst = new byte[0x31];
Buffer.BlockCopy(salt, 0, dst, 1, 0x10);
Buffer.BlockCopy(buffer2, 0, dst, 0x11, 0x20);
return Convert.ToBase64String(dst);
}验证：
public static bool VerifyHashedPassword(string hashedPassword, string password)
{
byte[] buffer4;
if (hashedPassword == null)
{
return false;
}
if (password == null)
{
throw new ArgumentNullException("password");
}
byte[] src = Convert.FromBase64String(hashedPassword);
if ((src.Length != 0x31) || (src[0] != 0))
{
return false;
}
byte[] dst = new byte[0x10];
Buffer.BlockCopy(src, 1, dst, 0, 0x10);
byte[] buffer3 = new byte[0x20];
Buffer.BlockCopy(src, 0x11, buffer3, 0, 0x20);
using (Rfc2898DeriveBytes bytes = new Rfc2898DeriveBytes(password, dst, 0x3e8))
{
buffer4 = bytes.GetBytes(0x20);
}
return ByteArraysEqual(buffer3, buffer4);
}Stack Overflow用户
发布于 2015-12-16 23:30:42
因为现在ASP.NET是开源的，你可以在GitHub上找到它：AspNet.Identity 3.0和AspNet.Identity 2.0。
从评论中：
/* =======================
* HASHED PASSWORD FORMATS
* =======================
*
* Version 2:
* PBKDF2 with HMAC-SHA1, 128-bit salt, 256-bit subkey, 1000 iterations.
* (See also: SDL crypto guidelines v5.1, Part III)
* Format: { 0x00, salt, subkey }
*
* Version 3:
* PBKDF2 with HMAC-SHA256, 128-bit salt, 256-bit subkey, 10000 iterations.
* Format: { 0x01, prf (UInt32), iter count (UInt32), salt length (UInt32), salt, subkey }
* (All UInt32s are stored big-endian.)
*/Stack Overflow用户
发布于 2016-02-13 04:51:44
对于像我这样的新手来说，这里是const的代码和比较byte[]的实际方法。
// 24 = 192 bits
private const int SaltByteSize = 24;
private const int HashByteSize = 24;
private const int HasingIterationsCount = 10101;
public static string HashPassword(string password)
{
// http://stackoverflow.com/questions/19957176/asp-net-identity-password-hashing
byte[] salt;
byte[] buffer2;
if (password == null)
{
throw new ArgumentNullException("password");
}
using (Rfc2898DeriveBytes bytes = new Rfc2898DeriveBytes(password, SaltByteSize, HasingIterationsCount))
{
salt = bytes.Salt;
buffer2 = bytes.GetBytes(HashByteSize);
}
byte[] dst = new byte[(SaltByteSize + HashByteSize) + 1];
Buffer.BlockCopy(salt, 0, dst, 1, SaltByteSize);
Buffer.BlockCopy(buffer2, 0, dst, SaltByteSize + 1, HashByteSize);
return Convert.ToBase64String(dst);
}
public static bool VerifyHashedPassword(string hashedPassword, string password)
{
byte[] _passwordHashBytes;
int _arrayLen = (SaltByteSize + HashByteSize) + 1;
if (hashedPassword == null)
{
return false;
}
if (password == null)
{
throw new ArgumentNullException("password");
}
byte[] src = Convert.FromBase64String(hashedPassword);
if ((src.Length != _arrayLen) || (src[0] != 0))
{
return false;
}
byte[] _currentSaltBytes = new byte[SaltByteSize];
Buffer.BlockCopy(src, 1, _currentSaltBytes, 0, SaltByteSize);
byte[] _currentHashBytes = new byte[HashByteSize];
Buffer.BlockCopy(src, SaltByteSize + 1, _currentHashBytes, 0, HashByteSize);
using (Rfc2898DeriveBytes bytes = new Rfc2898DeriveBytes(password, _currentSaltBytes, HasingIterationsCount))
{
_passwordHashBytes = bytes.GetBytes(SaltByteSize);
}
return AreHashesEqual(_currentHashBytes, _passwordHashBytes);
}
private static bool AreHashesEqual(byte[] firstHash, byte[] secondHash)
{
int _minHashLength = firstHash.Length <= secondHash.Length ? firstHash.Length : secondHash.Length;
var xor = firstHash.Length ^ secondHash.Length;
for (int i = 0; i < _minHashLength; i++)
xor |= firstHash[i] ^ secondHash[i];
return 0 == xor;
}在自定义ApplicationUserManager中，将PasswordHasher属性设置为包含上述代码的类的名称。
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原文链接：
https://stackoverflow.com/questions/20621950
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